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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Jeff,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I’m assuming that you mean that you are putting a 4kW Sunny Boy
out at the array, not a Sunny Island as you wrote.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The easy, albeit expensive, fix to the 120-240V problem is to
use two Sunny Islands, instead of an XW. You could also use two OutBack VFX3648’s.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>If you are going to use the Xantrex XW6048, you don’t also need
to use the Sunny Island. It’s an “either-or” not a “both”. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>You can use the XW in league with a Sunny Boy (or other grid-intertie
inverter) as an “AC Coupled” system, just like the Sunny Island/Sunny Boy
combo. The only difference (other than that the Sunny Island is only 120VAC) is
that the XW will not communicate with the Sunny Boy so you will have to place a
power relay in the AC line to the Sunny Boy, and control that relay with the
AUX output of the XW. When the grid is down, and the batteries are full, the
AUX output of the XW cuts the AC power to the Sunny Boy, shutting it down, and
preventing an overcharge on the battery bank. Set the AUX relay to operate at
the battery’s bulk voltage setting.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Put the Sunny Boy out at the array, and run it’s 240VAC output into
the sub-panel that is fed by the XW (with that power relay inline). When the
grid is up, the Sunny Boy’s power production is fed into the sub, then through
the XW’s transfer switch, and then into the main panel, and out to the grid.
This gives you the full efficiency of the Sunny Boy, without any losses from
the XW and battery. No transformers needed. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The generator is a bit more problematic. You will need a second
power relay in the Sunny Boy’s AC line that is only held closed when the grid
is up, but is open when the generator is providing the power. Power that relay
from the grid only to accomplish this. You will need a relay with a 120VAC or
240VAC coil. Connect the Sunny Boy to the NO contacts on the relay to act as a
fail-safe – if something were to happen to the AC connection to the relay, the
relay will fail open.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Using a single Sunny Island instead of the XW is not a great
idea. First you will need a transfer switch between the main panel and the Sunny
Island, that switches between the grid and the generator. Then you will need
two transformers - one to step the Sunny Island up to 240VAC to go into the
sub-panel, and another to step the grid/generator output of the transfer switch
down to 120VAC to go into the Sunny Island. In this case you will have to run a
com line out to the Sunny Boy, but you won’t need the overcharge relay. Be
aware, however, that this means that the PV’s power production has to always
run through both transformers, with the attendant transformer losses. It also
means that the connection to the grid is at 120VAC, so bigger wire and a larger
single-pole breaker is needed. You could eliminate one of the transformer’s
losses by installing it between the generator and the transfer switch, to step
the generator down to 120V, but then you are really getting out there in left
field.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>BTW – Xantrex has a White Paper out explaining how to use the XW
with Xantrex’s GT inverters in an AC Coupled system. The XW’s AUX output can
shut down GT’s without a separate relay. You might want to consider this combo.
Contact me off-list as the White Paper doesn’t appear to be on the Xantrex
website.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Cheers!<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Brian Teitelbaum<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>AEE Solar<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Jeff
Yago<br>
<b>Sent:</b> Thursday, May 28, 2009 6:55 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] AC Coupled (Again)<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Although
we have completed tons of grid-tie systems, and off-grid battery systems, this
will be our first AC coupled system and there are still a few things we need to
resolve. We will be using a 4 kW Sunny Island on a ground-mounted array
about 150 feet from home. We are considering using a Xantrex XW6048 since
we have both a grid connection and a backup generator and thought this would be
easier since everything will be 120/240 VAC except Sunny Island. We will
use a 120/240 Outback transformer to match the Sunny Island to the 240 volt
hardware.<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Here
are the issues that we are having a problem:<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>1.
Is this inverter match up the best since we have the 240 VAC grid, 240 VAC
generator, and a 240 VAC well pump on the back up panel? My concern with the
Sunny Island is it may require added issues with trying to connect to two
sources of AC power. <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2.
I know the Sunny Island "communicates" with the Sunny Boy by
altering ithe grid frequency it sees, but I am concerned this type of
control may not shut down the SunnyBoy when it sees power from the generator
and will still need a isolation relay. Is this a valid concern?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>3.
Looks like we will be in the 35 amp @ 120 VAC from the Sunny Island
back-feeding the backup power panel. Should we have the "relay"
to dis-connect the SunnyBoy when the grid is down and the battery is
full, or to avoid backfeed into the generator when the grid is down, but
what "relay"? Is there a specific model or size most
of you are using, or do we need a contactor instead of a "relay"
? What relay?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>4.
Do we need to run any control wiring out to the ground mounted array and remote
SunnyBoy to "signal" when we are dis-connecting it from the system
during the above conditions? I have installed some inverter brands
that were factory programmed to shut down when they exceed so many of the same
type outage condition "errors" thinking there was some kind of
system problem. <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Thanks
for the help,<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Jeff
Yago<o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><br>
<o:p></o:p></span></p>
<div class=MsoNormal align=center style='text-align:center'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Netscape.
Just the Net You Need.<o:p></o:p></span></p>
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